Without authorisation from the United Nations nuclear watchdog agency, Washington transferred 1.8 tonnes of enriched uranium, which could be used for making a "dirty bomb," from an Iraqi facility to an undisclosed location in the United States.

The uranium was looted when the Americans left the facility unguarded but most of it was recovered by the
International Atomic Energy Agency's inspectors as looters were more interested in containers than the uranium and just dumped it on the ground.

The uranium was kept under the seal of the IAEA before the US-led attack last year.

The US did inform the IAEA that it plans to shift the material for security reasons but did not seek or was granted an authorisation. The airlift was completed on June 23, five days before the US-led Coalition Authority transferred the sovereignty to the Iraqi interim government.

The shifting of the nuclear material without authorisation of the United Nations could be illegal, some world body officials say.

The uranium was from the Tuwaitha nuclear facility, about 20 km south of Baghdad. It was once a premium Iraqi facility for development of nuclear weapons but was dismantled in 1990s after the first Gulf war. The facility is now under the control of the new Iraqi interim government.

It was not clear where exactly the uranium is being kept, but American Energy Secretary Spencer Abraham described its removal as a "major achievement" in the Bush administration's goal of keeping "potentially dangerous nuclear material out of the hands of terrorists."

"It also puts this material out of reach for countries that may seek to develop their own nuclear weapons," Abraham said in a statement.

In a letter to the Security Council, IAEA Director General Mohammad El Baradei confirmed the transfer, saying that about 1.8 tonnes of uranium enriched to the level of 2.6 per cent had been transferred on June 23 along with 6.6 pounds of low enriched uranium and about 1000 highly radioactive sources.

He said the US had informed his agency on June 19 that it plans to shift some nuclear material from Tuwaitha for security reasons.

But the US claims that its action is in accordance with the Security Council resolutions and that it had briefed the Iraqi officials about the removal.

IAEA inspectors had left Iraq ahead of the last year US-led attack but were not allowed by Washington to return. However, it did allow them when reports of widespread looting of the material embarrassed the coalition authority.